Portable machining turntable

ABSTRACT

A Portable Machining Turntable (PMT) (1) used in combination with a milling, grinding or drilling machine (101) to allow both single and compound angles to be worked. The PMT (1) is comprised of an integral housing (2) enclosing an electric stepping motor (23) that through two pulleys (22), (24) and a timing belt (27) drives a worm drive assembly (17). The worm (21) drives a worm gear (43) that rotates a rotary head (36). The power to operate the motor (23) is supplied and controlled by a conventional numerical control system. However, the PMT (1) includes a mechanical override that allows the rotary head (36) to be manually rotated. To operate the PMT (1) it is mounted to a mill bed by standard clamp blocks inserted into hold-down slots (14) located on the lower walls of the housing (2). The work piece is then attached to the rotary head (36) and the head is rotated to the desired work angle. If compound angles are required the PMT (1) is secured to standard machine vise, attached to the mill bed, and positioned within the vise to provide the first angle. The second angle is then produced by rotating the rotary head in the prescribed manner.

TECHNICAL FIELD

This invention relates to rotary machining turntables and moreparticularly to portable machining turntables that can be electricallyor mechanically rotated to allow single or compound angles to be milled,ground and/or drilled.

BACKGROUND ART

The problems encountered by machinist in setting-up single andparticularly compound angles are enhanced by the unavailability of aneasy-to-operate and versatile rotary head. The heads presently availableare designed to be used either vertically or horizontally. To set-upcompound angles with this type of head, the head must be shimmed orblocked to produce the second angle of a compound angle. Additionally,incremental increases or decreases in the angular displacement aredifficult since for every change the shim must either be moved orincreased/decreased and the angle remeasured. This type of set-up is notcost-effective since it is very time consuming and must be made by anexperienced machinist.

A search of the prior art did not disclose any patents that disclosedthe versatility and ease of handling provided by the instant invention.However, the following U.S. patents were determined to be related:

    ______________________________________                                        U.S. PAT. NO.                                                                              INVENTOR     ISSUED                                              ______________________________________                                        4,274,773    Burkhardt    23 June 1981                                        3,273,879    Floren       20 September 1966                                   3,197,197    Butin        27 July 1965                                        ______________________________________                                    

The Burkhardt patent discloses a rotary index table comprising astationery table housing, a table plate for mounting the work piece anda rotation means mounted on the housing.

The Floren patent discloses a compound sine plate or holder which istiltable to provide a support surface at various angles for workingoperation.

The Butin patent discloses a device for holding work pieces on amachine-tool table which contains one longitudinal groove aid part forlocking a vise base to the machine table.

DISCLOSURE OF INVENTION

The Portable Machining Turntable (PMT) is used combination with amilling, grinding or drilling machine to allow both single and compoundangles to be worked. Two embodiments of the PMT are disclosed with thepreferred embodiment powered by an electrical motor with a mechanicaloverride and a solely mechanical model. The electrical model iscomprised of an integral housing enclosing an electric stepping motorthat through two pulleys and a timing belt turns a worm drive assemblyincorporating a worm. The worm drives a worm gear that in-turn rotates arotary head on which the work piece is mounted. The mechanical modelexcludes the electrical motor and associated components and ismechanically configured to allow the rotary head assembly to be rotatedby a socket wrench. The power to the stepping motor is supplied andcontrolled by a standard numerical control system that is not a part ofthe invention.

The PMT is operated by mounting it to the machine base by use ofstandard clamp blocks that are inserted into hold-down slots located onthe lower outside walls of the PMT housing. The work piece is thensecured to the top of the rotary head by means of the T-channel slotand/or the threaded mounting holes. Once the work piece is secured therotary head is rotated to the desired working angle. If a compound angleis required the PMT is clamped to a standard machine vise and the PMT ispositioned within the vise at any angle between 0 and 90 degrees toprovide the first angle. The second angle is then produced by rotatingthe rotary head in the prescribed manner.

In addition to providing an improved and simplified method foraccurately setting-up single and compound angles it is also an objectiveof the invention to provide an apparatus that:

is adaptable for use in large and small machine shops that mill, grindor drill,

can be easily set up and operated by one person

is reliable and easily maintainable.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of the Portable Machining Turntable (PMT) are described inconnection with the accompanying drawings in which:

FIG. 1 is an isometric view of the overall electrical PMT attached to amill bed.

FIG. 2 is an exterior side view of the electrical PMT.

FIG. 3 is a top view showing the T-channel and a typical mounting holeconfiguration of the rotary head.

FIG. 4 is a bottom view of the electrical PMT.

FIG. 5 is a cross-sectional side view of the electrical PMT.

FIG. 6 is a cross-sectional top view of the electrical PMT.

FIG. 7 is a cross-sectional view taken along lines 7--7 of FIG. 5showing the details of the shaft brake.

FIG. 8 is a cross-sectional view taken along lines 8--8 of FIG. 5showing the details of the worm drive assembly and worm gear.

FIG. 9 is an exploded view of the electrical PMT.

FIG. 10 is a side view of the manually operated PMT.

FIG. 11 is a cross-sectional side view of the manually operated PMT.

FIG. 12 is an exterior top view of the manually operated PMT.

FIG. 13 is an exterior bottom view of the manually operated PMT.

FIG. 14 is an exploded view of the manually operated PMT.

BEST MODE FOR CARRYING OUT THE INVENTION

The Portable Machining Turntable (PMT) 1 is described in terms of twoembodiments. The first embodiment described is considered the preferredand best mode forcarrying out the invention. The preferred embodimentfunctions primarily by electrical means and secondarily, if required, bymechanical means. The second embodiment performs the same function asthe first but functions solely by mechanical means. The numberingsequence from 1 through 49 is applicable to the first embodiment, from50 to 90 to the second embodiment; and 100 to 110 applies to itemsoutside the scope of the invention. The PMT 1 can be used in combinationwith a milling, grinding or drilling machine. However, for explanatorypurposes it is described in terms of its use with a milling machine.

The preferred embodiment of the PMT 1 is comprised of five major parts:an integral housing 2, a worm drive assembly 17, a worm gear 43, anelectric stepping motor 23, and a rotary head assembly 35.

The housing 2 is machined from an integral piece of material which inthe best mode is made of tool steel. The housing, as best shown in FIGS.1 and 5, has two cavities: a first cavity 3 extending upwardly from thebottom and a shallow second cavity 4 that extends over the opening ofthe first cavity 3. Within the limits of the first cavity 3 there islocated on one wall a first bore 6 that is in alinement with a partialsecond bore 7 located on the opposite wall. Within the first bore 6 andsecond bore 7 there is conventionally inserted a first bushing 15 and asecond bushing 16 respectively. The bushings are used to rotatablyattach a worm drive assembly 17, as best shown in FIG. 9, that iscomprised of: a worm drive shaft 18 where one end of the shaft isrotatably inserted and contained within the second bushing 16 and wherethe other end is rotatably inserted through the first bushing 15 andprotrudes through the first bore 6 and a worm shaft retaining nut 19.The retaining nut 19 has a slot 19a that allows the nut to be screwedinto the first bore 6. The protruding end of the shaft as shown in FIG.1 has a square end 18a that allows a socket wrench 88 to be attachedwhen mechanical rotation of the rotary head assembly 35 is required.

Located within the confines of the shaft 18 commencing from the secondbushing 16, is a worm 21. The worm 21 may be machined as an integralpart of the shaft 18 or may be inserted and radially locked by means ofa conventional locking key. Adjacent to the worm 21 is a first gearedpulley 22 that is radially locked by means of a locking key 26. A washer20 is next inserted that abutts against the first bushing 15 and theworm shaft retaining nut 19.

Within one of the inside walls of the first cavity 3, as shown in FIG.5, there is mounted, by conventional means, the electric stepping motor23. The motor is a type M091-FD09 or equivalent manufactured by MinarekElectric Company located in California, United States of America. Themotor is the best mode operates at 20 RPM, has a forward and reversecapability and is powered by a DC voltage applied through an electricalconnector 25 housed within a fourth bore 9 located on one of the housing2 walls. The power to the stepping motor 23 is supplied through a cableassembly 49 and is controlled by a standard numerical control system 100that is not a part of this invention.

Rigidly attached to the shaft of the motor 23 is a second geared pulley24 that is located on the same plane as the first geared pulley 22.Around the first and second geared pulley 22 and 24 is a timing belt 27.The belt 27 used in the preferred embodiment is a Gates timing beltmanufactured by the Gates Tire and Rubber Company located in Colorado,United States of America.

The first ball bearing race assembly 30 is set on top of the housing 2as best shown in FIG. 9. The assembly 30 is comprised of a circular racehaving a plurality of bore 31 housing on equal plurality of ballbearings 32. In the best mode there are twelve bores and twelve ballbearings. The assembly 30 also has a concentric bore 33.

The rotary head assembly 35 as shown in FIGS. 5 and 9 is comprised of acircular rotary head 36 that in the best mode has an integral concentricfirst shaft 37 and a contiguous second shaft 38 of a lessor diameterthan the first shaft 37. The bottom of the head 36 rests on top of thefirst ball bearing race assembly 30 with the first shaft 37 extendingthrough the bore 33 in the assembly 30 and through the third bore 8 inthe housing 2.

A second ball bearing race assembly 39 is constructed in a similarmanner as the first ball bearing race assembly 30 with the exceptionthat the diameter of the concentric hole is slightly smaller toaccommodate the diameter of the second shaft 38 of the rotary headassembly 35. The race assembly 39 is held against the bottom of thefirst shaft 37 by a pressure plate 41. By having two race assemblies 30,39 the rotary head 36 can be rotated with a minimum of friction.

The second shaft 38 is inserted through a second shaft bushing 40 thatis held in place by a spacer 42. The spacer 42 is sized to allow theworm gear 43 to be positioned on the shaft 38 so that it will mesh withthe worm 21 as shown in FIGS. 5 and 8. The worm gear is held in placeradially in the shaft 38 by a keylock 44 and is held laterally withinthe shaft 38 by a combination compression washer 45 and bolt 46.

Once the rotary head assembly 35 is rotated to the desired position thefirst shaft 37 is locked in place by a set of brakes 12 as shown in FIG.7. The brakes are adjusted by the brake screws 13 inserted in the firstthreaded hole 10 and second threaded hole 11.

When the PMT is in operation it is mounted on the mill bed 101, as shownin FIG. 1, by means of the clamp blocks 102 inserted into the hold-downslots 14 located on each outside lower wall of the housing 2. The workpiece 103 is mounted to the circular rotary head 36 by means of theT-channel slot 47 and/or the threaded holes 48 located in a mountingconfiguration as best shown in FIG. 12. If a larger work piece 103 is tobe worked it is mounted to an extension plate 90, as shown in FIG. 14,and the plate 90 is attached to the circular rotary head 36. The rotaryhead 36 is rotatable in one-degree increments and in the best mode thehead is rotated by electrical means. However, it is also possible torotate the head by mechanically rotating the shaft 18a by means of thesocket wrench 88.

When compound angles are required, the PMT 1 is secured to a standardmachine vise conventionally attached to the mill bed 101. The PMT isthen angularly positioned within the vise to provide the first angle.The second angle is then produced by rotating the rotary head 36 in theprescribed manner. To facilitate and stabilize the angular rotation ofthe housing 2 within the vise, a vise plate 29 as shown in FIG. 13 isset into one side of the vise jaws. The vise plate 29 consists of a 90degree angle plate that has a swivel pin 29a rigidly and conventionallyattached to the vertical external side of the plate. The pin 29a is theninserted into a corresponding partial swivel bore 28 located on one ofthe side walls of the housing 2 and the housing is rotated to thedesired angle. Once the angle is set the vise jaws are tightened tomaintain the selected angle.

The second embodiment of the PMT 1 is comprised of five major parts: anintegral housing 50, a worm drive assembly 60, a worm gear 75, a rotaryhead assembly 70, and a socket wrench 88.

The housing 50, as in the first embodiment, is machined from an integralpiece of material which in the best mode is made from tool steel. Thehousing, as best shown in FIGS. 10 and 11 has two cavities: a firstcavity 51 extending upwardly from the bottom; and a shallow secondcavity 52 that extends over the opening of the first cavity 51. Withinthe limits of the first cavity 51 there is located on one wall a firstbore 53 that is in alinement with a second bore 54 located on theopposite wall. Within the first bore 53 and second bore 54 there isconventionally inserted a first bushing 65 and a second bushing 66respectively. The bushings are used to rotatably house a worm driveassembly 60, as best shown in FIG. 14, that is comprised of a worm shaft62 and a worm 64. One end of the shaft is rotatably inserted andcontained within the second bushing 66 and the other end is rotatablyinserted through the first bushing 65 and protrudes through the firstbore 53. The shaft is held concentrically in place by a worm shaftretaining nut 63 that has a slot 63a that allows the nut to be screwedinto the first bore 53. The protruding end of the shaft as shown in FIG.12 has a square end 62a that allows the socket wrench 88 to be insertedwhen rotation of the rotary head assembly 70 is required. The secondembodiment also includes a worm shaft drag pin 61 that when the pin ispressed against the worm shaft 62 a shaft drag is produced. The pin 61,which is made of nylon and is partially threaded, is inserted into apartially threaded bore 67 extending upwardly from the top surface ofthe second cavity and is in alignment with the worm shaft 62. The dragpressure is set and made only once after which the bottom plate 68 isattached to the housing. The shaft drag prevents the shaft 62 fromrotating when the shaft is subjected to vibratory stresses duringmachine operation.

The rotary head assembly 70 is comprised of a circular rotary head 71that has extending from its bottom side an integral concentric firstshaft 72, a contiguous second shaft 73 having a lower threaded portionand of lessor diameter than the first shaft, and a contiguous thirdshaft 74 of lessor diameter than the second shaft 73.

The shaft 72 is inserted into the bore 86 of the ball bearing raceassembly 83 and through the third bore 55 of the housing 50. Theassembly 83 as in the best mode, is comprised of a circular race havingtwelve bores 84 housing an equal number of ball bearings 85. Theassembly 83 is sized to rest on top of the housing 50 as best shown inFIG. 11. Inserted into the second shaft 73 is the worm gear 75 which ispositioned on the shaft 73 so that it will mesh with the worm 64 as bestshown in FIG. 11. The worm gear is held in place radially in the shaft73 by a keylock 81 and is held laterally within the shaft by a spacer76. The spacer is held in place by a washer 77 and nut 78 combinationinserted into the threaded portion of the second shaft 73. The thirdshaft 74, as best shown in FIG. 11 is inserted into a third shaftbushing 79 that is held by friction in a cavity 69 located on the upperpart of the bottom plate 68. The bottom plate, which is sized to fitinto the second cavity 52 of the housing 50, is held in place by fourmachine screws threaded into the bottom of the second cavity 52.

Once the rotary head assembly 70 is rotated to the desired angularposition by the socket wrench 88, the second shaft 73 is locked in placeby a set of brakes 57 as shown in FIG. 11. The brakes are adjusted bythe brake screws 58 inserted into the threaded holes 56.

When the PMT is in operation, it is mounted to the mill bed 101, asshown in FIG. 1, by means of the hold-down slots 59 located on eachoutside lower wall of the housing 50. The work piece 103 is mounted tothe circular rotary head 36 by means of the T-channel slot 47 and/or thethreaded holes 48 located in a mounting configuration as best shown inFIG. 12. The mounting area of the circular rotary head 71 may beextended by attaching an extension mounting plate 90 as shown in FIG.14. The plate is attached to the circular rotary head 71 by two machinebolts.

If compound angles are required the PMT 1 can be secured to a standardmachine vise attached to the mill bed 101. The PMT is then angularlypositioned within the vise to provide the first angle. The second angleis then produced by rotating the head 71 in a conventional manner asdescribed supra.

I claim:
 1. A portable machining turntable comprising:(a) an integralelongated housing having two pairs of opposed parallel side wallsforming a square cross section adapted to be clamped by a standardmachine vise, and a top wall having a shallow third cavity or recess,said side walls and top forming a first cavity extending upwardly fromthe bottom, having a shallow second cavity extending over the opening ofthe first cavity, a first threaded bore located on one of the side wallsof the first cavity in alignment with a second bore located on theopposite side wall, a third bore extending from the top of said housingand aligned with the center of the first cavity, a first threaded holeextending through one of the side walls in alignment with a secondthreaded hole through the opposite side wall, and a plurality ofhold-down slots located in the lower outer sides of said said walls ofsaid housing, (b) a first bushing and a second bushing inserted withinthe first bore and second bore respectively, (c) a worm drive assemblycomprising:(1) a worm shaft where the ends of said shaft are rotatablyinserted and retained by said first bushing and said second bushing, (2)a worm rigidly attached to said shaft, (3) a first geared pulley rigidlyattached to said shaft, (4) a worm shaft retaining nut screwed into thefirst bore, where end of the worm shaft protrudes outside the nut, (d)an electric stepping motor rigidly mounted to one of the inside walls inthe first cavity of said housing, (e) a second geared pulley rigidlyattached to the shaft of said motor, and located on the same plane assaid first geared pulley, (f) a timing belt looped around and held tightby said first geared pulley and said second geared pulley, (g) a firstball bearing race assembly having a plurality of bores housing an equalplurality of ball bearings and having a central bore extendingtherethough where said assembly is set within the third cavity in saidhousing, (h) a rotary head assembly comprising:(1) a circular rotaryhead having a concentric first shaft and a contiguous second shaft oflesser diameter than the first shaft where a bottom of said head restson top of said first ball bearing race assembly and where the firstshaft extends through the bore in said first ball bearing race assemblyand through the third bore in said housing, (2) a second ball bearingrace assembly having a plurality of bores housing an equal plurality ofball bearings and having a central bore extending therethrough wheresaid assembly is inserted about the second shaft of said rotary head,(3) a bushing inserted into the second shaft, (4) a pressure plateinserted onto the second shaft of said rotary head around said bushingand thus maintains the second ball bearing race assembly against thebottom of the first shaft, (5) a spacer inserted onto the second shaftwhere an upper end of said spacer rests against the bottom of saidpressure plate, (6) a worm gear inserted onto the second shaft where itsupper end rests against the bottom of said spacer, such that said wormgear meshes with said worm, where said worm gear is held radiallystationery by a key lock and is maintained longitudinally in place by acombination compression washer and bolt inserted into the end of thesecond shaft, (i) a set of brakes and a corresponding set of brakeadjusting screws inserted into the first threaded hole and secondthreaded hole in said housing, (j) an electrical female plug externallyinserted through a fourth bore and attached to a wall of said housing,and (k) an electrical power cable having a corresponding male connectorthat attaches to said female plug and supplies the power to operate saidelectric stepping motor.
 2. A portable machining turntablecomprising:(a) an integral elongated housing having two pairs of opposedparallel side walls forming a square cross section adapted to be clampedby a standard machine vise, and a top wall having a shallow third cavityor recess, said side walls and top forming a first cavity extendingupwardly from the bottom, having a shallow second cavity extending overthe opening of the first cavity, a first threaded bore located on one ofthe side walls in alignment with a second bore located on the oppositeside wall, a third bore extending from the top of said housing andaligned with the center of the first cavity, (b) a first bushing and asecond bushing inserted within the first bore and second borerespectively, (c) a worm drive assembly comprising:(1) a worm shaftwhere the ends of said shaft are inserted and retained by said firstbushing and said second bushing, (2) a worm concentrically attached tosaid shaft, (3) a worm shaft retaining nut screwed into the first bore,where end of the worm shaft protrudes outside the nut, (d) a ballbearing race assembly having a plurality of bores housing an equalplurality of ball bearings and having a concentric bore extendingtherethrough where said assembly is set within the third cavity in saidhousing, (e) a rotary head assembly comprising:(1) a circular rotaryhead having a concentric shaft where bottom of said head rests on top ofsaid ball bearing race assembly and where the shaft extends through thebore in said ball bearing race assembly and through the the third borein said housing, (2) a worm gear attached to the bottom end of saidrotary head shaft where said worm gear meshes with said worm, a fourthpartially threaded bore extending upwardly from the top surface of thesecond cavity and in alignment with said worm shaft.
 3. The portablemachining turntable as specified in claim 1 or 2 wherein the externalside perimeter of said rotary head has marks incrementally spaced. 4.The portable machining turntable as specified in claims 1 or 2 whereinthe top of said rotary head has an inverted T-channel extending acrosssaid rotary head diameter and also having a plurality of threadedmounting holes.
 5. The portable machining turntable as specified inclaims 1 or 2 wherein said first and second bushings are made ofself-lubricating bronze.
 6. The portable machining turntable asspecified in claim 1 wherein said stepping motor in combination withsaid first and second geared pulleys and said timing belt steps inincrements corresponding to the incremental marks located on side ofsaid rotary head.
 7. The portable machining turntable as specified inclaims 1 or 2 further comprising a vise plate with a 90 degree angularplate sized to fit into one side of a standard machine vise jaw andhaving a swivel pin rigidly and conventionally attached to the verticalexternal side of said plate.
 8. The portable machining turntable asspecified in claim 7 wherein one side of said housing having a partialbore of slightly larger diameter than said swivel pin attached to saidvise plate.
 9. The portable machining turntable as specfied in claim 2further comprising a worm shaft drag pin that is partially threaded andthat is inserted into said fourth bore in said housing.
 10. The portablemachining turntable as specified in claims 1 or 2 further comprising asocket wrench sized to fit into the end of the protruding worm shaft ofsaid worm drive assembly.